#ifndef BumpMapping_h
#define BumpMapping_h

#include <cmath>

static int permutation[] = { 151,160,137,91,90,15,
   131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
   190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
   88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
   77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
   102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
   135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
   5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
   223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
   129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
   251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
   49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
   138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180
   };

static double fade( double t)
{
	return t * t * t * (t * (t * 6 - 15) + 10);
}

static double lerp(double t, double a, double b) {
    return a + t * (b - a);
}
static double grad(int hash, double x, double y, double z) {
    int h = hash & 15;
    double u = h<8||h==12||h==13 ? x : y,
            v = h<4||h==12||h==13 ? y : z;
    return ((h&1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
}


class BumpMapping
{
private:
	int p[512];
public:
	BumpMapping ()
	{
		for (int i=0; i < 256 ; i++) {
			p[256+i] = p[i] = permutation[i];
		}
	}
	int getP(int i){ return p[i];}
	double noise(double x, double y, double z) {

		BumpMapping myBumpMapping = BumpMapping();
		int X = (int)floor(x) & 255,
			Y = (int)floor(y) & 255,
			Z = (int)floor(z) & 255;
		x -= floor(x);
		y -= floor(y);
		z -= floor(z);
		double u = fade(x),
				v = fade(y),
				w = fade(z);
		int A = myBumpMapping.getP(X  )+Y, AA = myBumpMapping.getP(A)+Z, AB = myBumpMapping.getP(A+1)+Z,   
			B = myBumpMapping.getP(X+1)+Y, BA = myBumpMapping.getP(B)+Z, BB = myBumpMapping.getP(B+1)+Z;

		return lerp(w, lerp(v, lerp(u, grad(myBumpMapping.getP(AA  ), x  , y  , z   ),
										grad(myBumpMapping.getP(BA  ), x-1, y  , z   )),
								lerp(u, grad(myBumpMapping.getP(AB  ), x  , y-1, z   ), 
										grad(myBumpMapping.getP(BB  ), x-1, y-1, z   ))),
						lerp(v, lerp(u, grad(myBumpMapping.getP(AA+1), x  , y  , z-1 ),  
										grad(myBumpMapping.getP(BA+1), x-1, y  , z-1 )), 
								lerp(u, grad(myBumpMapping.getP(AB+1), x  , y-1, z-1 ),
										grad(myBumpMapping.getP(BB+1), x-1, y-1, z-1 ))));
	}
};

#endif
